#include <iostream>
using namespace std;

class animal
{
    public:
        void sleep()
        {
            cout<<"animal sleep"<<endl;
        }
        void breathe()
        {
            cout<<"animal breathe"<<endl;
        }
};
class fish:public animal
{
    public:
        void breathe()
        {
            cout<<"fish bubble"<<endl;
        }
};
int main()
{
    fish fh;
    animal *pAn=&fh; // 隐式类型转换
    pAn->breathe();
    return 0;
}